# vite-library-config

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## Purpose

`createViteLibraryConfig` builds an opinionated Vite `UserConfig` suitable for any `@suaveplan/*` library package. It encodes the suaveplan conventions for tree-shake-friendly output, type-declaration emission via `vite-plugin-dts`, and the `external` baseline (`/^@suaveplan\//`, `/^node:/`, `'tslib'`). Every package in the project can drop a one-line `vite.config.ts` and inherit the contract: ESM-first output with `preserveModules`, named exports, and sourcemaps.

## Features

- `preserveModules: true` with `preserveModulesRoot` mirroring the source root.
- `vite-plugin-dts` plugin pre-pended ahead of caller-supplied plugins.
- `external` automatically merged with the suaveplan baseline.
- Zod-validated option boundary; bad input throws `TestViteError(TEST_VITE.INVALID_OPTIONS)`.
- OTel counter `test_vite_config_built_total{kind="vite_library"}` incremented per invocation.

## Usage: Basic

```ts
// vite.config.ts
import { createViteLibraryConfig } from "@suaveplan/test-vite/vite-library-config";

export default createViteLibraryConfig({
  entries: { index: "src/index.ts" },
  tsconfigPath: "./tsconfig.lib.json",
});
```

## Usage: Advanced

Multi-entry build with extra externals and caller plugins:

```ts
import path from "node:path";
import { createViteLibraryConfig } from "@suaveplan/test-vite/vite-library-config";

export default createViteLibraryConfig({
  root: __dirname,
  entries: {
    index: "src/index.ts",
    "submodule/index": "src/submodule/index.ts",
  },
  entryRoot: "src",
  outDir: "dist",
  tsconfigPath: "./tsconfig.lib.json",
  external: ["zod", /^@opentelemetry\//],
  plugins: [],
  sourcemap: true,
  emptyOutDir: true,
});
```

## API Reference

- `createViteLibraryConfig(opts: ViteLibraryConfigOptions): UserConfig`.
- `ViteLibraryConfigOptions` — `{ root?, entries, tsconfigPath?, entryRoot?, outDir?, external?, sourcemap?, emptyOutDir?, plugins? }`.
- Throws `TestViteError` with code `TEST_VITE.INVALID_OPTIONS` on Zod failure.

## Implementation Notes

The factory mutates nothing on the input; the returned config is freshly constructed. Rollup `output.entryFileNames` is set to `[name].js` so the emitted directory mirrors the source tree. The dts plugin is added with `insertTypesEntry: true` so a single `index.d.ts` shim is emitted for the package root regardless of how many entries are configured. The `external` baseline is intentionally merged via simple concatenation rather than de-duplication so caller-supplied entries always take precedence in Rollup's match order.